Regulating transformer system



April 25; 1950 F. HQJOHN Er'AL REGULATING TRANSFORIH! SYSTEM F1106 Jan. 28, 1947 $47URATED OUT OUT

NON- SATURATED /NVENTOI?$ FRANK Al. J HN IMBY Patented Apr. 25, 1950 REGULATING TRANSFORMER SYSTEM Frank H. John, San Francisco, Calf., and Robert S: Quimby, Lexington, Mass., asslgnors to Raytheon Manufacturing Company, Newton, Mass., a corporation of Delaware Application January 28, 1947, Serial No. 724,854

4 Claims.

This invention relates to alternating current :egulating systems of the magnetic or inductive ype.

It is an important object of this invention to provide an improved form of alternating current voltage regulating system having a regulated output voltage of substantially sinusoidal waveform.

It is another object of this invention to provide a system of voltage, regulation for alternating current, the system employing a number of transformers, inductances and condensers to obtain a regulated output voltage of substantially sinusoidal waveform which is relatively devoid of harmonics whereby the relationship between peak, average, and R. M. S. output voltages is almost exactly the same as a sine wave and wherein simultaneous vo'tage regulation to close limits of the peak, average, and R. M. S. values of output voltage is obtained. I

Further objects and advantages of this invention will be apparent upon reference to the following specification and: drawing in which:

Fig. l is a schematic diagram of one form of the invention;

Fig. 2 is a schematic diagram of another form of the invention; and

Fig. 3 is a schematic diagram of yet another form of the invention.

One of the magnetic or transformer types of inductance is resonated to the fundamental frequency of the line votage by a parallelconnected condenser or impedance of opposite sign and, since its inductance is substantially saturated, the impedance of the resonant circuit thus obtained in series with the line and the other impedance is extremely variable for slight line voltage changes. Each of the impedances has secondary windings inductively related thereto and the connections of the elements in the system Y are such, as set forth in the prior patent, to pro duce a regulated voltage output for considerable variations of voltage input. The waveform of the regulated voltage output from such-a system is not sinusoidal, it being rich in third and fifth harmonics of the fundamental as well as numerous other odd harmonics to a lesser extent.

It has been discovered by this invention that the presence of the odd harmonic waveforms in the regulated voltage output from such a system is due to an inherent function of the saturated inductance operating near the bend of its saturation curve which, in order to produce a sinusoidal voltage output, requires an input containing certain oddharmonio currents in amounts according to the exact point on the saturation curve that the inductance is operating. The supply of such harmonic currents from the fundamental line frequency to the saturated inductance is ordithe resultant voltage output will be substantially sinusoidal and devoid of harmonics.

The system shown" by Fig. 1 of the drawing provides one means of supplying harmonic currents of the fundamental line frequency to the primary of a saturated transformer used in such system. Terminals l0 and II are connected to. the alternating current line of a known fundamental frequency such as, for example, sixty cycles per second. The regulated voltage output of the system appears at the terminals l2 and II. A non-saturated transformer l4 and a saturated autotransformer l5 are provided with their primaries l6 and I! connected in series with the line voltage at terminals l0 and II and their secondaries l8 and i1 connected in series opposition with theoutput terminals 12 and 13. Connected across the winding of the saturated autotransformer I5 is a condenser is adapted to resohate the tuned circuit comprised of primary I1 and condenser l9 to the line frequency. Thus far, the voltage regulating or stabilizing system is conventional. In order to supply certain harmonic currents of the line frequency to the saturated prlmary ii, in accordance with the teachings of this invention, to provide a substantially sinusoidal waveform for the output voltage, a. series tuned resonant circuit comprising the condenser 20 and inductance 2i is connected across the primary l6 of transformer M in series with the saturated primary l1. With the series tuned circuit adapted to resonate, at a selected harmonic, for example the third harmonic of the line frequency, it will be apparent that such harmonic current is bypassed around the non-saturated impedance of winding I6 or, in other words, is generated from the fundamental line frequency to be supplied to the saturated primary ll so that its output voltage will be substantially sinusoidal and devoid of the third harmonic. It should be understood that the selection of a particular harmonic frequency or combination of harmonic frequencies for the series tuned circuit or circuits is a matter of choice as determined by the desired quality of sinusoidal waveform for the output' voltage and the number of harmonics to be eliminated in the output voltage. Also it should be resonated at the fifth harmonic.

noted that although a saturated core autotransformer of one-to-one ratio has been described, the system of the invention is not limited to the use of such ratio or autotransformer. For example, conventional insulated transformers of either step-up or step-down ratios may be used and such is done in the system of Fig. 3 to be later described.

A somewhat modified form of regulating system having means for applying certain fundamental currents of the line frequency to the saturated primary winding is shown in Fig. 2 of the drawing. Elements of the system which are the same as in the system of Fig. 1 will be given identical reference numerals and will not be further described. It will be noted that in this form of the invention the series tuned resonant circuit comprised of condenser and inductance 2|, tuned to a harmonic of the fundamental line frequency, is connected in parallel to the saturated primary winding ll instead of in parallel to the non-saturated primary I 8 as shown by Fig. 1. In both systems the results are the same, the series tuned circuit functioning to generate a selected harmonic current of the fundamental line frequency and apply it across the terminals of saturated primary i! so as to obtain substantially sinusoidal waveforms for the regulated voltage output.

The system of Fig. 3 is somewhat different. A non-saturated transformer Ill and a saturated transformer ll are provided with their primaries I2 and 33 connected in series with the line input terminals I4 and 85 and their secondaries and 31 connected in series opposition to the output terminals It and 19. Connected across the saturated primary I3 is a pair of series tuned circuits l4 and 35, respectively. including condensers ll and 31 and inductances 3! and 39, respectively. One of the series tuned circuits 3 or 35 may be designed to resonate at the third harmonic of the fundamental line frequency and the other may be It should be mentioned that in such an arrangement neither of the inductances 38 and I9 offers a substantial impedance to the fundamental line frequency so that the condensers 38 and 31 may simultaneously function to resonate the saturated primary 33 to the fundamental line frequency, thus eliminating the condenser I! shown in the systems of Figs. 1 and 2. It should be apparent that the waveform of the voltage output from the system of Fig. 3 will be substantially more sinusoidal than that obtained from the systems of Figs. 1 and 2 since it is substantially more devoid of harmonic content, both the third and fifth harmonics being substantially eliminated. Obviously additional series tuned circuits for other odd harmonic frequencies, such as the seventh, ninth etc., may be used alone or together where a specifically desired quality of sinusoidal waveform for the output voltage is desired.

It is not intended that this invention be limited to the specific systems described since it is apparent that equivalent means for generating certain odd harmonic currents of the line frequency and applying them to the saturated core magnetic winding in such regulating systems will occur to those skilled in the art.

What is claimed is:

1. A voltage regulating system comprising two impedances in series with each other and with a source of alternating current, one of said impedances comprising an inductance and a capacity in parallel, said inductance having a magnetic core and being designed to operate near its saturation point, means by-passing the other of said impedances to apply one or more selected odd harmonic currents of the fundamental line frequency to said inductance, and windings inductlvely related to said impedances, said windings being connected in series opposition whereby a regulated voltage having a waveform substantially devoid of the selected harmonics is obtained between two spaced points on said windings.

2. A voltage regulating system comprising two transformers, means connecting the primaries of said transformers in series with each other and a source of alternating current, an iron core for each of said transformers, one of said cores being magnetically saturated and the other core being magnetically unsaturated, means to resonate the primary of the saturated core transformer to the fundamental line frequency, and means connected across the primary of the unsaturated core transformer to apply one or more selected odd harmonic currents of the fundamental frequency to the primary of the saturated core transformer, the secondaries of said transformers being connected in'series opposition whereby a resultant regulated voltage having a waveform substantially devoid of the selected harmonics is obtained across said secondaries.

3. A voltage regulating system comprising two impedances in series with each other and with a source of alternating current, one of said impedances comprising an inductance and a capacity in parallel, said inductance having a magnetic core and being designed to operate near its saturation point, means comprising one or more series resonant circuits tuned to one or more selected odd harmonic frequencies of said fundamental frequency and connected in parallel with one of said impedances, and windings coupled to said impedances and connected in series opposition with respect to each other whereby a regulated voltage having a waveform substantially devoid of the selected harmonics is obtained between two spaced points on said windings.

4. A voltage regulating system comprising two transformers, means connecting the primaries of said transformers in series with each other and a source of alternating current, an iron core for each of said transformers, one of said cores being magnetically saturated and the other core being mangetically unsaturated, means to resonate the primary of the saturated core transformer to the fundamental line frequency, means comprising one or more series resonant circuits tuned to one or more selected odd harmonics of said fundamental frequency and connected in I parallel with the primary of the unsaturated core transformer, and means connecting the secondaries of said transformers in series opposition whereby a resultant regulated voltage having a waveform substantially devoid of the selected harmonics is obtained across said secondaries.

FRANK H. JOHN. ROBERT S. QUIMBY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,179.353 Schmutz et a1. Nov. 7, 1939 2,442,214 Short May 24, 1948 FOREIGN PATENTS Number Country Date 463 947 Great Britain Apr. 5, 1937 548,526 Great Britain Oct. 12, 1942 Certificate of Correction Patent N 0. 2,505,620 April 25, 1950 FRANK H. JOHN ET AL It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 4, line 38, for the word one read the other;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 18th day of July, A. D. 1950.

[sun] JOE E. DANIELS,

Assistant Commissioner of Patents.

Certificate of Correction Patent No. 2,505,620 April 25, 1950 FRANK H. JOHN ET AL It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 4, line 38, for the word one read the other;

and that the said Letters Patent should be read with this correction therein that the same may conform to the record of the case in the Patent Oflice.

Signed and sealed this 18th day of July, A. D. 1950.

[sun] JOE E. DANIELS,

Assistant Oommissz'oner of Patents.

Certificate of Correction Patent N 0. 2,505,620 April 25, 1950 FRANK H. JOHN ET AL It is hereby certified that error appears in the printed specification of the above numbered patent requiring correction as follows:

Column 4, line 38, for the word one read the other;

and that the said Letters Patent should be read with this correction therein that the some may conform to the record of the case in the Patent Ofiice.

Signed and sealed this 18th day of July, A. D. 1950.

JOE E. DANIELS,

Assistant Commissioner of Patents. 

